Mongodb Condition

1.count Count returns the number of documents in the collection &http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;db.refactor.count () No matter how large the collection is, the number of documents can be returned quickly. You can pass the query, MongoDB calculates the number of query results Db.refactor.count ({...).

MongoDB released the 1.6.0 version, which is the fourth major stable version of the 1.0,1.2,1.4 version, and released the 1.6.1 release on August 17. This release focuses on enhanced dynamic expansion (Scale-out) features, http://www.aliyun.com/zixun/aggregation/14273.html ">sharding functionality is already available in the production environment." Use both horizontal and replication collections (replica sets ...).

&http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;1.find MongoDB uses Find to query. The query is to return a subset of the files in the set. The child collection ranges from 0 documents to the entire collection. The first parameter of find determines which documents to return. The form is also a document that describes the details to be queried. The empty query document {} matches the entire contents of the collection. If you don't specify ...

The scalability of the system is the main reason for promoting the development of NoSQL movement, including distributed system coordination, failover, resource management and many other features. That makes NoSQL sound like a big basket that can be stuffed with anything. Although the NoSQL movement does not bring fundamental technological changes to distributed data processing, it still leads to extensive research and practice on protocols and algorithms. It is through these attempts to gradually summarize some effective database construction methods. In this article, I will focus on the NoSQL database distributed special ...

The scalability of the system is the main reason for promoting the development of NoSQL movement, including distributed system coordination, failover, resource management and many other features. That makes NoSQL sound like a big basket that can be stuffed with anything. Although the NoSQL movement does not bring fundamental technological changes to distributed data processing, it still leads to extensive research and practice on protocols and algorithms. It is through these attempts to gradually summarize some effective database construction methods. In this article, I will focus on the distributed features of the NoSQL database ...

Pinterest has maintained an exponential growth that will be doubled every 1.5 months. In two years, they achieved PV from 0 to tens of billions of, from the beginning of the two founder plus an engineer to now more than 40 engineers, from a small MySQL server to 180 web Enigne, 240 API Enigne, 88 MySQL DB (Cc2.8xlarge, each DB will be configured with a slave node), 110 Redis instance and 200 Mmecach ...

Successive China Cloud computing Conference has become the landmark event of IT industry development. In 2009, the first Congress discussed cloud computing and its scope; in 2010, the second Congress defined cloud computing hotspot technologies and applications; In 2011, the third Congress discussed the relationship with traditional operators and shared cloud computing practices; 2012, the fourth session of the General Assembly defines "the first year of cloud computing practice," In-depth analysis of technology and industry experience, OpenStack, Cloudstack, Hadoop and other platform research harmonizing; 2013, the fifth session of the General Assembly ...

Taxis, buses, passenger buses, heavy goods vehicles ..., operating vehicles occupy an important position in urban traffic, and people's lives and even social development has an important relationship. 　　It has become an indispensable part of intelligent traffic construction to build an information platform, monitor and manage the operating vehicles, standardize the vehicle behavior and establish a good operation order. "National Transportation Supervision Service Platform" is one of the important products developed by Beijing Zhong Xing Road Information Technology Co., Ltd. (hereinafter referred to as "Zhong Xing Lu"), which is committed to the monitoring, management and information interaction of the national freight vehicle, in full ...

"Editor's note" WiX has been operating the site for a long time, and after the launch of the WYSIWYG web platform based on HTML5, users have established more than 54 million sites in the company, and most of these sites have less than 100 solar PV. Since the PV of each page is low, the traditional caching strategy does not apply. Even so, however, the company has done so with only 4 Web servers. Recently, WiX chief back-end engineer Aviran Mordo in "...